WEEK 1 - Introduction to Urinalysis 2

What is urine best characterized as?

Ultrafiltrate of plasma

What is the most abundant organic component of urine?

Urea

What is the most abundant inorganic component of urine?

Chloride

What percentage of urine is water?

95%

What percentage of urine is solutes?

5%

What is urea the end product of?

Protein catabolism

What is creatinine a product of?

Creatine metabolism in muscles

What is the average daily urine output?

1,200–1,500 mL/day

What is the normal range of random daily urine output?

600–2,000 mL/day

What is the normal day-to-night (D/N) ratio of urine output?

2–3:1

What condition is defined as persistent urine output greater than 2,500 mL/day?

Polyuria

What urine condition is associated with diabetes mellitus and high specific gravity?

Polyuria

What condition is associated with diabetes insipidus and low specific gravity?

Polyuria

What condition is defined as urine output less than 400 mL/day?

Oliguria

What are clinical causes of oliguria?

Dehydration, renal insufficiency, heart disease, calculi, kidney tumors

What condition refers to total suppression of urine production?

Anuria or Anuresis

What are clinical causes of anuria?

Severe acute nephritis, mercury poisoning, obstructive uropathy, kidney failure

What condition is defined as nighttime urine output greater than 500 mL with specific gravity

Nocturia

What are physiologic causes of nocturia?

Pregnancy, elderly age

What is a pathologic cause of nocturia?

Prostatic enlargement

What is the term for transitory increase in urine volume, often due to diuretics?

Diuresis

What is the most concentrated urine specimen of the day?

First morning specimen

Which specimen is preferred for routine urinalysis, pregnancy tests, and detection of orthostatic proteinuria?

First morning specimen

Why is the first morning specimen preferred for testing?

It is the most concentrated specimen of the day

What is orthostatic (postural) proteinuria?

Persistent benign proteinuria after standing, disappearing when lying down

Who commonly experiences orthostatic proteinuria?

Young adults

What causes orthostatic proteinuria?

Increased pressure on the renal vein in the vertical position

What is the protein result in an afternoon (PM) specimen in orthostatic proteinuria?

Positive

What is the protein result in a first morning specimen that confirms benign orthostatic proteinuria?

Negative

If protein is still positive in the first morning specimen, what does it suggest?

Renal disease

What type of urine specimen is most commonly used for routine urinalysis?

Random specimen

What can cause false negative or falsely low results in a random specimen?

Dilutional effect due to water intake

What condition can random specimens help detect when evaluating renal disease?

Orthostatic proteinuria

What is the purpose of timed urine specimens?

For quantitative chemical tests, hormone studies, and clearance tests

What equipment is required for timed urine specimen collection?

Requisition form, 24-hour container with lid, label, ice (if needed), preservative (if required)

What should be done before collecting a timed urine specimen?

Provide written instructions and explain the procedure to the patient

At what time does the 24-hour urine collection begin?

Day 1 at 7 a.m. – patient voids and discards specimen

At what time does the 24-hour urine collection end?

Day 2 at 7 a.m. – patient voids and adds the specimen to collection

What is done after the 24-hour urine is collected?

The entire specimen is mixed, volume measured, and 50 mL is aliquoted for testing

What happens to the rest of the 24-hour urine specimen after aliquoting?

It is discarded

Why must the collection start and end with an empty bladder?

To ensure accuracy of the 24-hour collection

How much urine does the collection container need to accommodate in a 24-hour specimen?

600–2000 mL (normal) or >2.5 L (polyuria)

What is the required urine amount for testing from a 24-hour collection?

Approximately 50 mL

What is the purpose of the 24-hour urine specimen?

Quantitative chemical tests, hormone studies, clearance tests

What is the purpose of the 12-hour urine specimen?

Addis’ count (counting formed elements in urine)

What preservative is used in a 12-hour Addis' count specimen?

Formalin

What is the purpose of a 2-hour afternoon urine specimen collected from 2–4 p.m.?

Urobilinogen determination

What container is used for a 2-hour afternoon specimen?

Amber bottle

What type of specimen is used for fasting diabetic screening?

Second morning urine specimen

Why is the first morning urine discarded in fasting diabetic screening?

It may contain metabolites from previous meals and give false-positive glucose results

Why is the second morning specimen preferred for fasting diabetic screening?

It reflects urine produced during fasting and is more accurate for glucose testing

What is the best urine specimen type for detecting glycosuria/glucosuria?

2-hour post-prandial urine specimen

What happens to blood glucose 2 hours after a meal in non-diabetics?

It returns to normal; no glucose appears in urine

What happens to blood glucose 2 hours after a meal in diabetics?

It remains elevated, exceeding renal threshold, causing glycosuria

What is the role of GTT urine specimen?

Used previously as accompaniment to blood specimens in OGTT

What is the purpose of a drug testing urine specimen?

To detect presence of drugs in the body

What is added to toilet water during an unwitnessed drug test collection to prevent adulteration?

Bluing agent (dye)

What is the minimum required volume of urine for drug testing?

30 to 45 mL

What is the acceptable urine temperature range for drug testing specimens?

32.5°C to 37.7°C

What must be done if urine temperature is out of range during drug testing?

Recollect specimen and notify supervisor

What form documents every step of the drug testing process?

Chain of Custody (COC) form

What is the purpose of a witnessed urine collection in drug testing?

To ensure the urine is truly from the donor and prevent tampering

What type of specimen is collected midstream after cleaning the genital area?

Midstream clean-catch

What is the use of a midstream clean-catch specimen?

Routine urinalysis and bacterial culture

What method involves inserting a catheter into the bladder to collect urine?

Catheterization

What is the use of a catheterized urine specimen?

Bacterial culture

What is the most sterile method of urine collection involving needle aspiration?

Suprapubic aspiration

What are the uses of a suprapubic aspiration specimen?

Bacterial culture and cytology

What is the purpose of prostatitis specimens?

To diagnose prostatic infections using specialized urine collection techniques

How many portions of urine are collected in the three-glass collection method?

Three portions

What does Tube 1 represent in the three-glass collection method?

First portion of voided urine (initial urine)

What does Tube 2 represent in the three-glass collection method?

Midstream urine; control for kidney and bladder infections

What does Tube 3 represent in the three-glass collection method?

Final portion of urine after prostatic massage; contains prostatic secretions

What is the interpretation of Tube 3 in three-glass collection if prostatic infection is present?

WBC and bacterial counts are significantly elevated—typically 10× higher than Tube 1

What does a high WBC/bacterial count in Tube 2 indicate?

Possible kidney or bladder infection

Why is prostatic massage done before collecting Tube 3?

To release prostatic secretions into the remaining urine for analysis

What does the four-glass collection method include that the three-glass method does not?

Expressed Prostatic Secretion (EPS) collected during prostatic massage

What is another name for the four-glass collection method?

Meares-Stamey Test

What are the components of the four-glass collection method?

Tube 1 (initial voided urine), Tube 2 (midstream urine), EPS (expressed prostatic secretion), Tube 3 (post-massage urine)

How is EPS collected in the four-glass collection?

Collected during prostatic massage in a separate container

What does Tube 3 in the four-glass method contain?

Post-massage urine containing EPS + urine

What is the interpretation of EPS and Tube 3 in the four-glass collection if prostatitis is present?

Significantly elevated WBC and bacterial counts confirming prostatic infection

What is the role of Tube 1 and Tube 2 in the four-glass collection?

Serve as controls for urethral and bladder infections respectively